In U.S. Pat. No. 4,515,343, there is taught a contact damper at one end of the travel of the armature to provide dampening as the armature approaches the pole piece. In other systems, the power to the actuator is applied to move the armature across the gap and when the armature is close to the stator, a magnetic force from the stator coil is removed to slow down the armature and hope for a "soft", near zero velocity, landing. Just before the landing, the stator coil is then re-energized to pull the armature into a landing. The actuator has at least two opposing springs which sequentially release their potential energy to move the armature from one stator pole to the other. The stator coils, i.e. the receiving coil when energized, adds enough force to the stored up and released spring force to move and seat the armature.
The purpose of the actuator is to open and close an engine valve of an internal combustion engine.
The problem is to devise a control algorithm that provides enough extra energy from the stator coils to always complete the armature travel during a stroke but at the same time produce a "soft" (near zero velocity) landing of the armature against a stator to prevent excessive impact wear on the armature and stator and to reduce the amount of noise produced by such impact.